Analysis of the prevalence and species of Anisakis nematode in Sekisaba, Scomber japonicus caught in coastal waters off Saganoseki, Oita in Japan.

Abstract

Anisakidosis is developed by ingesting Anisakis in marine fish including the chub mackerel, Scomber japonicus without proper pre-treatment such as cooking or freezing. Two sibling species of Anisakis are found in S. japonicus from Japanese waters and the prevalence and species of Anisakis in the fish depend on sea area. For example, Anisakis simplex sensu stricto is found in the Pacific stock of S. japonicus, while Anisakis pegreffii is found in the Tsushima Warm Current stock. S. japonicus caught in the Bungo Channel, off the coast of Saganoseki in Oita Prefecture, which is branded as Sekisaba, inhabits a very limited area; however, the infection states of Anisakis found in Sekisaba remain unclear. In this study, we compared the infection states of Anisakis in Sekisaba with those in S. japonicus caught in South Oita area and Nagasaki Prefecture. All of Anisakis from Nagasaki Prefecture were A. pegreffii, while most of them found in Sekisaba and fish from South Oita area were A. simplex s.s.. Interestingly, the prevalence of Anisakis in Sekisaba was significantly lower than those of two other areas. This may be reflected that Sekisaba might belong to a distinct stock of S. japonicus varying from other stocks.